Computers networks are known systems which are widely used. It is not an exaggeration to say that almost every personal computer (PC) is the node of at least one computer network. Methods of providing a network user with an automatic notification from the network server are also known and used especially for notifying a subscriber of the receipt of messages, addressed to the subscriber and which are stored in an electronic mail block of the server. To this end, a successful notification requires that the subscriber's PC be continually connected to the network server, i.e. be in a so-called `on-line` mode of operation.
A system of this kind is disclosed, for example, in U.S. Pat. No. 5,138,653. The system comprises a microprocessor and a random access memory connected to an electronic mail system for receiving data items which identify the queuing messages. The access memory is organized so as to form a file containing codes which identify predetermined addresses of subscribers to whom messages are to be sent and data items representing the telephone numbers of these addresses. The system also comprises a modem connected to a telephone line for extracting the telephone number data items from the file and automatically dialing the telephone numbers of the addresses in order to transmit call signals to the respective subscriber through the telephone line. The microprocessor reads the queuing file of the messages, detects the presence of the identification codes residing in the file for extracting from the file the telephone number data item corresponding to each identification code detected, and instructs the modem to dial automatically the corresponding call numbers. Thus, the addresses of received messages are notified immediately by telephone of the receipt of these messages and quickly receive the latter without the need for special stand-by.
It will be appreciated that such `on-line` connection to the network server results in the following two limitations for the user:
1) telephone bill derived according to the call tariff and duration of the call;
2) the availability of the telephone line is compromised because most users do not have a dedicated computer phone line and are thus occupying the main home line during the connection.
Moreover, in the case of such a network as so-called `INTERNET` which is also known and widely used, an additional bill would be received from the Internet Service Provider, which bill is also derived from the respective call tariff and duration.
Another problem that exists today is the relatively complex set of operations a user has to perform to work on-line. Indeed, the user has to connect, operate the specific application to obtain the required information, and disconnect. All these operations are semi-manual in today's popular home operation systems such as, for example, MS-Windows. Novice users regard the on-line processes such as, for example, checking mail as cumbersome and error prone because of the lines being busy or/and owing to slow responses times, etc. Even advanced users regard the on-line processes as a nuisance and try to automate them as much as possible, for example, by using scripts, automatic dialers, etc.
A system for mail notification has been developed and disclosed in European Patent Publication No. EP 0 736 989. The system comprises a host computer and subscriber computers, wherein the subscriber computers are not connected to each other and/or the host computer. Messages are sent from a `sender` subscriber to a `recipient` subscriber via the host computer which is adapted for storing mail addressed to subscribers in individual mail boxes. The host computer is adapted for calling a phone associated with the recipient subscriber through a dialing unit whenever a new message arrives at the host computer. The dialing unit is connected through a telephone line, or a public telephone network to a receiving unit located at the recipient's side. The receiving unit is a specific hardware unit which is either stand alone, or a constructional part of the recipient's PC. Even in such a case that the recipient himself directly contacts the dialing unit through a conventional modem coupled to or installed in his PC, a notification arrives all the same to the receiving unit. More specifically, a notification enters a call intercept unit which is integral with the receiving unit. The receiving unit identifies that the phone call has been sent by the dialing unit of the host computer. A dedicated display device must be associated with the receiving unit for indicating to the subscriber that a notification has been received. It is thus evident that the disclosed system requires, in addition to specific hardware accommodated at the host computer's side, the provision of additional hardware at each subscriber's side.
Additionally, it is often the case that a subscriber, even being in a so-called `off-line` mode of operation needs to be automatically informed that the network server has been updated with a specific information of interest to the subscriber since his/her last connection. This information may be supplied to the network server by either another subscriber or specific data base commonly connected to the server. Alternatively, the case may be such that one subscriber needs to be connected to another subscriber through one or more network servers. In this case, the other subscriber, who may not be currently connected `on-line` to the associated server should be informed that the specific subscriber desires to contact him.